diff --git a/_demo/catomic/atomic.go b/_demo/catomic/atomic.go
index e2ab9163..9125f42d 100644
--- a/_demo/catomic/atomic.go
+++ b/_demo/catomic/atomic.go
@@ -1,20 +1,20 @@
 package main
 
 import (
-	"github.com/goplus/llgo/c"
 	"github.com/goplus/llgo/c/sync"
 )
 
 func main() {
 	var v int64 = 100
 	ret := sync.FetchAndAdd(&v, 1)
-	c.Printf(c.Str("FetchAndAdd: %ld, new: %ld\n"), ret, v)
+	println("ret:", ret, "v:", v)
 
-	chg := sync.CompareAndXchg(&v, 100, 102)
-	c.Printf(c.Str("CompareAndXchg: %ld, 100, new: %ld\n"), v, chg)
-	chg = sync.CompareAndXchg(&v, 101, 102)
-	c.Printf(c.Str("new: %ld, CompareAndXchg: %ld, 101\n"), v, chg)
+	ret = sync.CompareAndXchg(&v, 100, 102)
+	println("ret:", ret, "vs 100, v:", v)
+
+	ret = sync.CompareAndXchg(&v, 101, 102)
+	println("ret:", ret, "vs 101, v:", v)
 
 	ret = sync.FetchAndSub(&v, 1)
-	c.Printf(c.Str("FetchAndSub: %ld, new: %ld\n"), ret, v)
+	println("ret:", ret, "v:", v)
 }
diff --git a/cl/_testlibc/atomic/in.go b/cl/_testlibc/atomic/in.go
index c448d16d..8c05f87a 100644
--- a/cl/_testlibc/atomic/in.go
+++ b/cl/_testlibc/atomic/in.go
@@ -15,4 +15,7 @@ func main() {
 
 	sync.CompareAndXchg(&v, 101, 102)
 	c.Printf(c.Str("%ld\n"), v)
+
+	sync.FetchAndSub(&v, 1)
+	c.Printf(c.Str("%ld\n"), v)
 }